Williams, 32, a three-time Oscar nominee, has been seeing Segel, 33, a star of How I Met Your Mother, for about a year, and were seen together as recently as January vacationing in Cancun, Mexico.

But they were not an out-and-about couple. Segel, 33, was said to be obsessively in love with the actress with the winsome blond pixie cut, and they seemed happy for a while.

But distance may have been a problem: He lives in Los Angeles and Williams lives in New York with Matilda, 7, her daughter with her ex, the late Australian actor Heath Ledger.

Williams, who was nominated for Oscars for My Week With Marilyn (2011), Blue Valentine (2010) and Brokeback Mountain (2005), will be seen next as Glinda in Oz the Great and Powerful, opening next week. Segel was in 2012's This is 40.